Light Therapy for Obsessive-compulsive Disorder (OCD)

Prior to the start of this study, there are screening procedures to ensure participants meet the criteria for the study. At the first consent screening appointment, participants will learn more about the study and answer questionnaires. All of the results of the screening procedures are confidential and will only be used by the study staff to determine eligibility for the study. This study is 5 weeks long and involves 4 in-person lab visits at the Sleep and Chronobiology Lab. Participants will be randomly assigned to either an active or placebo light therapy treatment condition. Visit 1 will involve additional screening to determine eligibility, including questionnaires and interviews. If eligible, participants will then track their sleep for 2 weeks at home with a wrist-worn activity monitor and a sleep diary. Visit 2 will take place in the lab from 5:30pm until 1 hour after participants typical bedtime. The investigators will ask participants to provide saliva samples hourly to measure melatonin and complete questionnaires. The investigators will provide treatment instructions at this visit. Investigators will then ask participants to engage in the treatment at home for 3 weeks. Investigators will schedule 1 in-person visit (Visit 3) and 1 phone call to assess adherence to the treatment during these 3 weeks. Visit 4 will take place in the lab after the treatment is finished. Visit 4 will last from 5:30pm until 1.5 hours after participants typical bedtime and will involve hourly saliva samples to measure melatonin, questionnaires, and interviews.